Physics - P2.5: Radioactivity

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  • Created by: shcoool
  • Created on: 26-05-15 17:20
What is the structure of an atom?
A nucleus with protons and neutrons surrounded with electrons
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What are relative masses and charges of the subatomic particles?
proton: +1, 1; neutron: 0, 1; electron: -1, 0
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Describe an atom
same number of protons as electrons, no overall electrical charge
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How do atoms become ions?
They gain or lose electrons
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What do protons in and atom represent?
Atoms of the same number have the same number of protons. The number is called its atomic number
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What is an isotope?
Atoms that have the same number of protons bu a different number of neutrons?
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What is the mass number?
The total number of protons and neutrons
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What are radioactive substances?
Substances that give out radiation from the nuclei of their atoms all the time, whatever is done to them
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Give some examples of sources of background radiation
natural - cosmic rays, rocks and soil man-made - fall-out from nuclear bombs, tests and accidents, smoke detectors, x-rays
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What is an alpha particle?
Two neutrons and two protons (a helium nucleus)
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What is a beta particle?
An electron from a neutron that split into a proton and electron. The proton remained in the nucleus
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What is gamma radiation?
electromagnetic radiation (often after alpha or beta)
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How does the element mass number and atomic number change after beta and alpha radiation?
alpha - mass number decreases by four and atomic number decreases by two; beta - mass number stays the same and atomic number increased by one
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What can the three types of radiation penetrate?
alpha - stopped by paper or thin sheet of aluminium, beta - penetrates thin aluminium sheet but stopped by thicker sheet, gamma - penetrates aluminium but stopped by thick sheet of lead
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What is the half-life of an element?
The average time it takes for half of atoms to decay
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What is the ionising power of the three types of radiation?
alpha - intense ionisation of a gas, beta - less ionisation, gamma - minimal ionisation
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How are the three types of radiation affected by electric and magnetic fields?
alpha - defected slightly, beta - defected easily, gamma - not affected
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What are the ranges of each type of radiation through air?
alpha - few cm, beta - several metres, gamma -
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Name two fissionable substances commonly used in reactors
uranium - 235 and plutonium - 239
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What is nuclear fission?
The splitting of an atomic nucleus
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What has to happen for fission to occur?
the nuclear substances must absorb a neutron
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What happens to the nucleus undergoing fission?
Splits into two smaller nuclei and 2 or 3 neutrons fall out and energy is released
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Draw the chain the reaction of nuclear fission
(Drawing)
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What is the moderator, control rod and coolant in a nuclear power plant?
moderator - slows down neutrons without absorbing them, control rod - materials that absorbs the neutrons slowing the reaction, coolant - substance that transports the heat from the core
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Other cards in this set

Card 2

Front

What are relative masses and charges of the subatomic particles?

Back

proton: +1, 1; neutron: 0, 1; electron: -1, 0

Card 3

Front

Describe an atom

Back

Preview of the front of card 3

Card 4

Front

How do atoms become ions?

Back

Preview of the front of card 4

Card 5

Front

What do protons in and atom represent?

Back

Preview of the front of card 5
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